This is an oldie-but-goodie – the LM3914 is an analog-input LED driver. That means you can feed it an analog voltage input and it will light up LEDs in order, ideal for a no-microcontroller LED VU meter, or battery meter, or spectrum analyzer (when combined with some band-pass filters). Has nice extras like constant-current drive, and DIP size. I think these are rather cute!
All this and more, in the PART FINDER!

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The LM3914/15/16′s are a trio of analog input led drivers. The 14 responds to a linear voltage, the 15 is 3dB per step and the 16 is for an led VU meter. All handy for different applications.
Comment by David Bley — April 13, 2012 @ 7:39 pm
If you want to make a true LED VU meter, use the LM3915 because it has its comparators set for 3-dB steps. The LM3916 could have 1, 2, or 3-dB steps, I believe, depending on the input level.
Comment by Rusty — April 14, 2012 @ 12:45 am
I stand corrected. Thanks David!
Comment by Rusty — April 14, 2012 @ 6:33 pm